﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Drawing.Design;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;
using Windows.Win32.UI.Input.KeyboardAndMouse;

namespace System.Windows.Forms.Design.Behavior;

/// <summary>
///  The BehaviorService essentially manages all things UI in the designer.
///  When the BehaviorService is created it adds a transparent window over the
///  designer frame.  The BehaviorService can then use this window to render UI
///  elements (called Glyphs) as well as catch all mouse messages.  By doing
///  so - the BehaviorService can control designer behavior.  The BehaviorService
///  supports a BehaviorStack.  'Behavior' objects can be pushed onto this stack.
///  When a message is intercepted via the transparent window, the BehaviorService
///  can send the message to the Behavior at the top of the stack.  This allows
///  for different UI modes depending on the currently pushed Behavior.  The
///  BehaviorService is used to render all 'Glyphs': selection borders, grab handles,
///  smart tags etc... as well as control many of the design-time behaviors: dragging,
///  selection, snap lines, etc...
/// </summary>
public sealed partial class BehaviorService : IDisposable
{
    private readonly IServiceProvider _serviceProvider;             // standard service provider
    private readonly AdornerWindow _adornerWindow;                  // the transparent window all glyphs are drawn to
    private readonly List<Behavior> _behaviorStack;                 // the stack behavior objects can be pushed to and popped from
    private Behavior? _captureBehavior;                              // the behavior that currently has capture; may be null
    private Glyph? _hitTestedGlyph;                                  // the last valid glyph that was hit tested
    private IToolboxService? _toolboxSvc;                            // allows us to have the toolbox choose a cursor
    private Control? _dropSource;                                    // actual control used to call .dodragdrop
    private DragEventArgs? _validDragArgs;                           // if valid - this is used to fabricate drag enter/leave events
    private BehaviorDragDropEventHandler? _beginDragHandler;         // fired directly before we call .DoDragDrop()
    private BehaviorDragDropEventHandler? _endDragHandler;           // fired directly after we call .DoDragDrop()
    private EventHandler? _synchronizeEventHandler;                  // fired when we want to synchronize the selection
    private TRACKMOUSEEVENT _trackMouseEvent;                       // demand created (once) used to track the mouse hover event
    private bool _trackingMouseEvent;                               // state identifying current mouse tracking
    private string[]? _testHook_RecentSnapLines;                     // we keep track of the last snaplines we found - for testing purposes
    private bool _useSnapLines;                                     // indicates if this designer session is using snaplines or snapping to a grid
    private bool _queriedSnapLines;                                 // only query for this once since we require the user restart design sessions when this changes
    private readonly HashSet<Glyph> _dragEnterReplies;              // we keep track of whether glyph has already responded to a DragEnter this D&D.

    // test hooks for SnapLines
    private static MessageId WM_GETALLSNAPLINES { get; } = PInvoke.RegisterWindowMessage("WM_GETALLSNAPLINES");
    private static MessageId WM_GETRECENTSNAPLINES { get; } = PInvoke.RegisterWindowMessage("WM_GETRECENTSNAPLINES");

    private const string ToolboxFormat = ".NET Toolbox Item"; // used to detect if a drag is coming from the toolbox.

    internal BehaviorService(IServiceProvider serviceProvider, DesignerFrame windowFrame)
    {
        _serviceProvider = serviceProvider;
        _adornerWindow = new AdornerWindow(this, windowFrame);

        // Use the adornerWindow as an overlay
        IOverlayService? os = serviceProvider.GetService<IOverlayService>();
        if (os is not null)
        {
            AdornerWindowIndex = os.PushOverlay(_adornerWindow);
        }

        _dragEnterReplies = [];

        // Start with an empty adorner collection & no behavior on the stack
        Adorners = new BehaviorServiceAdornerCollection(this);
        _behaviorStack = [];

        _hitTestedGlyph = null;
        _validDragArgs = null;
        DesignerActionUI = null;
        _trackMouseEvent = default;
        _trackingMouseEvent = false;

        // Create out object that will handle all menucommands
        IMenuCommandService? menuCommandService = serviceProvider.GetService<IMenuCommandService>();
        IDesignerHost? host = serviceProvider.GetService<IDesignerHost>();
        if (menuCommandService is not null && host is not null)
        {
            MenuCommandHandler menuCommandHandler = new(this, menuCommandService);
            host.RemoveService<IMenuCommandService>();
            host.AddService<IMenuCommandService>(menuCommandHandler);
        }

        // Default layoutmode is SnapToGrid.
        _useSnapLines = false;
        _queriedSnapLines = false;

        // Listen to the SystemEvents so that we can resync selection based on display settings etc.
        SystemEvents.UserPreferenceChanged += new UserPreferenceChangedEventHandler(OnUserPreferenceChanged);
    }

    /// <summary>
    ///  Read-only property that returns the AdornerCollection that the BehaviorService manages.
    /// </summary>
    public BehaviorServiceAdornerCollection Adorners { get; }

    /// <summary>
    ///  Returns the actual Control that represents the transparent AdornerWindow.
    /// </summary>
    internal Control AdornerWindowControl => _adornerWindow;

    internal int AdornerWindowIndex { get; } = -1;

    internal bool HasCapture => _captureBehavior is not null;

    /// <summary>
    ///  Returns the LayoutMode setting of the current designer session.  Either SnapLines or SnapToGrid.
    /// </summary>
    internal bool UseSnapLines
    {
        get
        {
            // we only check for this service/value once since we require the  user to re-open the designer session
            // after these types of option have been modified
            if (!_queriedSnapLines)
            {
                _queriedSnapLines = true;
                _useSnapLines = DesignerUtils.UseSnapLines(_serviceProvider);
            }

            return _useSnapLines;
        }
    }

    /// <summary>
    ///  Creates and returns a Graphics object for the AdornerWindow
    /// </summary>
    public Graphics AdornerWindowGraphics
    {
        get
        {
            Graphics result = _adornerWindow.CreateGraphics();
            result.Clip = new Region(_adornerWindow.DesignerFrameDisplayRectangle);
            return result;
        }
    }

    public Behavior? CurrentBehavior => _behaviorStack.Count > 0 ? _behaviorStack[0] : null;

    internal bool Dragging { get; private set; }

    internal bool CancelDrag { get; set; }

    internal DesignerActionUI? DesignerActionUI { get; set; }

    /// <summary>
    ///  Called by the DragAssistanceManager after a snapline/drag op has completed - we store this data for
    ///  testing purposes. See TestHook_GetRecentSnapLines method.
    /// </summary>
    internal string[] RecentSnapLines
    {
        set => _testHook_RecentSnapLines = value;
    }

    /// <summary>
    ///  Disposes the behavior service.
    /// </summary>
    public void Dispose()
    {
        // Remove adorner window from overlay service
        IOverlayService? os = _serviceProvider.GetService<IOverlayService>();
        os?.RemoveOverlay(_adornerWindow);

        if (_serviceProvider.GetService(typeof(IMenuCommandService)) is MenuCommandHandler menuCommandHandler &&
            _serviceProvider.GetService(typeof(IDesignerHost)) is IDesignerHost host)
        {
            IMenuCommandService oldMenuCommandService = menuCommandHandler.MenuService;
            host.RemoveService<IMenuCommandService>();
            host.AddService(oldMenuCommandService);
        }

        _adornerWindow.Dispose();
        SystemEvents.UserPreferenceChanged -= new UserPreferenceChangedEventHandler(OnUserPreferenceChanged);
    }

    [MemberNotNull(nameof(_dropSource))]
    private Control DropSource => _dropSource ??= new Control();

    internal DragDropEffects DoDragDrop(DropSourceBehavior dropSourceBehavior)
    {
        // Hook events
        DropSource.QueryContinueDrag += new QueryContinueDragEventHandler(dropSourceBehavior.QueryContinueDrag);
        DropSource.GiveFeedback += new GiveFeedbackEventHandler(dropSourceBehavior.GiveFeedback);

        DragDropEffects res = DragDropEffects.None;

        // Build up the eventargs for firing our dragbegin/end events
        ICollection dragComponents = ((DropSourceBehavior.BehaviorDataObject)dropSourceBehavior.DataObject).DragComponents;
        BehaviorDragDropEventArgs eventArgs = new(dragComponents);

        try
        {
            try
            {
                OnBeginDrag(eventArgs);
                Dragging = true;
                CancelDrag = false;

                // This is normally cleared on OnMouseUp, but we might not get an OnMouseUp to clear it. VSWhidbey #474259
                // So let's make sure it is really cleared when we start the drag.
                _dragEnterReplies.Clear();
                res = DropSource.DoDragDrop(dropSourceBehavior.DataObject, dropSourceBehavior.AllowedEffects);
            }
            finally
            {
                DropSource.QueryContinueDrag -= new QueryContinueDragEventHandler(dropSourceBehavior.QueryContinueDrag);
                DropSource.GiveFeedback -= new GiveFeedbackEventHandler(dropSourceBehavior.GiveFeedback);

                // If the drop gets cancelled, we won't get a OnDragDrop, so let's make sure that we stop
                // processing drag notifications. Also VSWhidbey #354552 and 133339.
                EndDragNotification();
                _validDragArgs = null;
                Dragging = false;
                CancelDrag = false;
                OnEndDrag(eventArgs);
            }
        }
        catch (CheckoutException cex)
        {
            if (cex == CheckoutException.Canceled)
            {
                res = DragDropEffects.None;
            }
            else
            {
                throw;
            }
        }
        finally
        {
            // It's possible we did not receive an EndDrag, and therefore we weren't able to cleanup the drag.
            // We will do that here. Scenarios where this happens: dragging from designer to recycle-bin,
            // or over the taskbar.
            dropSourceBehavior.CleanupDrag();
        }

        return res;
    }

    internal void EndDragNotification() => _adornerWindow.EndDragNotification();

    private void OnEndDrag(BehaviorDragDropEventArgs e) => _endDragHandler?.Invoke(this, e);

    private void OnBeginDrag(BehaviorDragDropEventArgs e) => _beginDragHandler?.Invoke(this, e);

    /// <summary>
    ///  Translates a point in the AdornerWindow to screen coords.
    /// </summary>
    public Point AdornerWindowPointToScreen(Point p) => _adornerWindow.PointToScreen(p);

    /// <summary>
    ///  Gets the location (upper-left corner) of the AdornerWindow in screen coords.
    /// </summary>
    public Point AdornerWindowToScreen() => AdornerWindowPointToScreen(new Point(0, 0));

    /// <summary>
    ///  Returns the location of a Control translated to AdornerWindow coords.
    /// </summary>
    public Point ControlToAdornerWindow(Control c)
    {
        if (c.Parent is null)
        {
            return Point.Empty;
        }

        Point pt = new(c.Left, c.Top);
        PInvoke.MapWindowPoints(c.Parent, _adornerWindow, ref pt);
        if (c.Parent.IsMirrored)
        {
            pt.X -= c.Width;
        }

        return pt;
    }

    /// <summary>
    ///  Converts a point in handle's coordinate system to AdornerWindow coords.
    /// </summary>
    public Point MapAdornerWindowPoint(IntPtr handle, Point pt)
    {
        PInvoke.MapWindowPoints((HWND)handle, _adornerWindow, ref pt);
        return pt;
    }

    /// <summary>
    ///  Returns the bounding rectangle of a Control translated to AdornerWindow coords.
    /// </summary>
    public Rectangle ControlRectInAdornerWindow(Control c)
    {
        if (c.Parent is null)
        {
            return Rectangle.Empty;
        }

        Point loc = ControlToAdornerWindow(c);
        return new Rectangle(loc, c.Size);
    }

    /// <summary>
    ///  The BehaviorService fires the BeginDrag event immediately before it starts a drop/drop operation
    ///  via DoBeginDragDrop.
    /// </summary>
    public event BehaviorDragDropEventHandler? BeginDrag
    {
        add => _beginDragHandler += value;
        remove => _beginDragHandler -= value;
    }

    /// <summary>
    ///  The BehaviorService fires the EndDrag event immediately after the drag operation has completed.
    /// </summary>
    public event BehaviorDragDropEventHandler? EndDrag
    {
        add => _endDragHandler += value;
        remove => _endDragHandler -= value;
    }

    /// <summary>
    ///  The BehaviorService fires the Synchronize event when the current selection should be synchronized (refreshed).
    /// </summary>
    public event EventHandler? Synchronize
    {
        add => _synchronizeEventHandler += value;
        remove => _synchronizeEventHandler -= value;
    }

    /// <summary>
    ///  Given a behavior returns the behavior immediately after the behavior in the behaviorstack.
    ///  Can return null.
    /// </summary>
    public Behavior? GetNextBehavior(Behavior behavior)
    {
        if (_behaviorStack.Count > 0)
        {
            int index = _behaviorStack.IndexOf(behavior);
            if ((index != -1) && (index < _behaviorStack.Count - 1))
            {
                return _behaviorStack[index + 1];
            }
        }

        return null;
    }

    internal void EnableAllAdorners(bool enabled)
    {
        foreach (Adorner adorner in Adorners)
        {
            adorner.EnabledInternal = enabled;
        }

        Invalidate();
    }

    /// <summary>
    ///  Invalidates the BehaviorService's AdornerWindow.  This will force a refresh of all Adorners
    ///  and, in turn, all Glyphs.
    /// </summary>
    public void Invalidate() => _adornerWindow.InvalidateAdornerWindow();

    /// <summary>
    ///  Invalidates the BehaviorService's AdornerWindow.  This will force a refresh of all Adorners
    ///  and, in turn, all Glyphs.
    /// </summary>
    public void Invalidate(Rectangle rect) => _adornerWindow.InvalidateAdornerWindow(rect);

    /// <summary>
    ///  Invalidates the BehaviorService's AdornerWindow.  This will force a refresh of all Adorners
    ///  and, in turn, all Glyphs.
    /// </summary>
    public void Invalidate(Region r) => _adornerWindow.InvalidateAdornerWindow(r);

    /// <summary>
    ///  Synchronizes all selection glyphs.
    /// </summary>
    public void SyncSelection() => _synchronizeEventHandler?.Invoke(this, EventArgs.Empty);

    /// <summary>
    ///  Removes the behavior from the behavior stack
    /// </summary>
    public Behavior? PopBehavior(Behavior behavior)
    {
        if (_behaviorStack.Count == 0)
        {
            throw new InvalidOperationException();
        }

        int index = _behaviorStack.IndexOf(behavior);
        if (index == -1)
        {
            Debug.Assert(false, $"Could not find the behavior to pop - did it already get popped off? {behavior}");
            return null;
        }

        _behaviorStack.RemoveAt(index);
        if (behavior == _captureBehavior)
        {
            _adornerWindow.Capture = false;

            // Defensive:  adornerWindow should get a WM_CAPTURECHANGED, but do this by hand if it didn't.
            if (_captureBehavior is not null)
            {
                OnLoseCapture();
                Debug.Assert(_captureBehavior is null, "OnLostCapture should have cleared captureBehavior");
            }
        }

        return behavior;
    }

    internal void ProcessPaintMessage(Rectangle paintRect)
    {
        // Note, we don't call BehSvc.Invalidate because this will just cause the messages to recurse.
        // Instead, invalidating this adornerWindow will just cause a "propagatePaint" and draw the glyphs.
        _adornerWindow.Invalidate(paintRect);
    }

    /// <summary>
    ///  Pushes a Behavior object onto the BehaviorStack.  This is often done through hit-tested Glyph.
    /// </summary>
    public void PushBehavior(Behavior behavior)
    {
        ArgumentNullException.ThrowIfNull(behavior);

        // Should we catch this
        _behaviorStack.Insert(0, behavior);

        // If there is a capture behavior, and it isn't this behavior, notify it that it no longer has capture.
        if (_captureBehavior is not null && _captureBehavior != behavior)
        {
            OnLoseCapture();
        }
    }

    /// <summary>
    ///  Pushes a Behavior object onto the BehaviorStack and assigns mouse capture to the behavior.
    ///  This is often done through hit-tested Glyph.  If a behavior calls this the behavior's OnLoseCapture
    ///  will be called if mouse capture is lost.
    /// </summary>
    public void PushCaptureBehavior(Behavior behavior)
    {
        PushBehavior(behavior);
        _captureBehavior = behavior;
        _adornerWindow.Capture = true;

        // VSWhidbey #373836. Since we are now capturing all mouse messages, we might miss some WM_MOUSEACTIVATE
        // which would have activated the app. So if the DialogOwnerWindow (e.g. VS) is not the active window,
        // let's activate it here.
        IUIService? uiService = _serviceProvider.GetService<IUIService>();
        if (uiService?.GetDialogOwnerWindow() is { } hWnd && hWnd.Handle != 0 && hWnd.Handle != PInvoke.GetActiveWindow())
        {
            PInvoke.SetActiveWindow(new HandleRef<HWND>(hWnd, (HWND)hWnd.Handle));
        }
    }

    /// <summary>
    ///  Translates a screen coord into a coord relative to the BehaviorService's AdornerWindow.
    /// </summary>
    public Point ScreenToAdornerWindow(Point p) => _adornerWindow.PointToClient(p);

    internal void OnLoseCapture()
    {
        if (_captureBehavior is not null)
        {
            Behavior b = _captureBehavior;
            _captureBehavior = null;
            try
            {
                b.OnLoseCapture(_hitTestedGlyph, EventArgs.Empty);
            }
            catch
            {
            }
        }
    }

    private bool PropagateHitTest(Point pt)
    {
        for (int i = Adorners.Count - 1; i >= 0; i--)
        {
            if (!Adorners[i].Enabled)
            {
                continue;
            }

            for (int j = 0; j < Adorners[i].Glyphs.Count; j++)
            {
                Cursor? hitTestCursor = Adorners[i].Glyphs[j].GetHitTest(pt);
                if (hitTestCursor is not null)
                {
                    // InvokeMouseEnterGlyph will cause the selection to change, which might change the number of glyphs, so we need to remember the new glyph before calling InvokeMouseEnterLeave. VSWhidbey #396611
                    Glyph newGlyph = Adorners[i].Glyphs[j];

                    // with a valid hit test, fire enter/leave events
                    InvokeMouseEnterLeave(_hitTestedGlyph, newGlyph);
                    if (_validDragArgs is null)
                    {
                        // if we're not dragging, set the appropriate cursor
                        SetAppropriateCursor(hitTestCursor);
                    }

                    _hitTestedGlyph = newGlyph;
                    // return true if we hit on a transparentBehavior, otherwise false
                    return (_hitTestedGlyph.Behavior is ControlDesigner.TransparentBehavior);
                }
            }
        }

        InvokeMouseEnterLeave(_hitTestedGlyph, null);
        if (_validDragArgs is null)
        {
            Cursor cursor = Cursors.Default;
            if (_behaviorStack is [Behavior behavior, ..])
            {
                cursor = behavior.Cursor;
            }

            SetAppropriateCursor(cursor);
        }

        _hitTestedGlyph = null;

        // Returning false will cause the transparent window to return HTCLIENT when handling WM_NCHITTEST,
        // thus blocking underline window to receive mouse events.
        return true;
    }

    internal void StartDragNotification() => _adornerWindow.StartDragNotification();

    private MenuCommand? FindCommand(CommandID commandID, IMenuCommandService menuService)
    {
        Behavior? behavior = GetAppropriateBehavior(_hitTestedGlyph);

        if (behavior is not null)
        {
            if (behavior.DisableAllCommands)
            {
                MenuCommand? menuCommand = menuService.FindCommand(commandID);

                if (menuCommand is not null)
                {
                    menuCommand.Enabled = false;
                }

                return menuCommand;
            }
            else
            {
                // Check to see if the behavior wants to interrupt this command
                MenuCommand? menuCommand = behavior.FindCommand(commandID);
                if (menuCommand is not null)
                {
                    // The behavior chose to interrupt - so return the new command
                    return menuCommand;
                }
            }
        }

        return menuService.FindCommand(commandID);
    }

    private Behavior? GetAppropriateBehavior(Glyph? g)
    {
        return _behaviorStack.Count > 0 ? _behaviorStack[0] : g?.Behavior;
    }

    private void ShowError(Exception ex)
    {
        _serviceProvider.GetService<IUIService>()?.ShowError(ex);
    }

    private void SetAppropriateCursor(Cursor cursor)
    {
        // Default cursors will let the toolbox svc set a cursor if needed
        if (cursor == Cursors.Default)
        {
            _toolboxSvc ??= _serviceProvider.GetService<IToolboxService>();

            if (_toolboxSvc is not null && _toolboxSvc.SetCursor())
            {
                cursor = new Cursor(PInvoke.GetCursor());
            }
        }

        _adornerWindow.Cursor = cursor;
    }

    private void InvokeMouseEnterLeave(Glyph? leaveGlyph, Glyph? enterGlyph)
    {
        if (leaveGlyph is not null)
        {
            if (enterGlyph is not null && leaveGlyph.Equals(enterGlyph))
            {
                // Same glyph - no change
                return;
            }

            if (_validDragArgs is not null)
            {
                OnDragLeave(leaveGlyph, EventArgs.Empty);
            }
            else
            {
                OnMouseLeave(leaveGlyph);
            }
        }

        if (enterGlyph is not null)
        {
            if (_validDragArgs is not null)
            {
                OnDragEnter(enterGlyph, _validDragArgs);
            }
            else
            {
                OnMouseEnter(enterGlyph);
            }
        }
    }

    private void OnDragEnter(Glyph? g, DragEventArgs e)
    {
        // If the AdornerWindow receives a drag message, this method will be called without
        // a glyph - assign the last hit tested one
        g ??= _hitTestedGlyph;

        Behavior? behavior = GetAppropriateBehavior(g);
        if (behavior is null)
        {
            return;
        }

        behavior.OnDragEnter(g, e);

        if (g is ControlBodyGlyph && e.Effect == DragDropEffects.None)
        {
            _dragEnterReplies.Add(g);
        }
    }

    private void OnDragLeave(Glyph? g, EventArgs e)
    {
        // This is normally cleared on OnMouseUp, but we might not get an OnMouseUp to clear it. VSWhidbey #474259
        // So let's make sure it is really cleared when we start the drag.
        _dragEnterReplies.Clear();

        // If the AdornerWindow receives a drag message, this method will be called without
        // a glyph - assign the last hit tested one
        g ??= _hitTestedGlyph;

        Behavior? behavior = GetAppropriateBehavior(g);
        if (behavior is null)
        {
            return;
        }

        behavior.OnDragLeave(g, e);
    }

    private bool OnMouseDoubleClick(MouseButtons button, Point mouseLoc)
        => GetAppropriateBehavior(_hitTestedGlyph)?.OnMouseDoubleClick(_hitTestedGlyph, button, mouseLoc) ?? false;

    private bool OnMouseDown(MouseButtons button, Point mouseLoc)
        => GetAppropriateBehavior(_hitTestedGlyph)?.OnMouseDown(_hitTestedGlyph, button, mouseLoc) ?? false;

    private bool OnMouseEnter(Glyph? g) => GetAppropriateBehavior(g)?.OnMouseEnter(g) ?? false;

    private bool OnMouseHover(Point mouseLoc)
        => GetAppropriateBehavior(_hitTestedGlyph)?.OnMouseHover(_hitTestedGlyph, mouseLoc) ?? false;

    private bool OnMouseLeave(Glyph? g)
    {
        // Stop tracking mouse events for MouseHover
        UnHookMouseEvent();
        return GetAppropriateBehavior(g)?.OnMouseLeave(g) ?? false;
    }

    private bool OnMouseMove(MouseButtons button, Point mouseLoc)
    {
        // Hook mouse events (if we haven't already) for MouseHover
        HookMouseEvent();
        return GetAppropriateBehavior(_hitTestedGlyph)?.OnMouseMove(_hitTestedGlyph, button, mouseLoc) ?? false;
    }

    private bool OnMouseUp(MouseButtons button)
    {
        _dragEnterReplies.Clear();
        _validDragArgs = null;
        return GetAppropriateBehavior(_hitTestedGlyph)?.OnMouseUp(_hitTestedGlyph, button) ?? false;
    }

    private unsafe void HookMouseEvent()
    {
        if (!_trackingMouseEvent)
        {
            _trackingMouseEvent = true;
            _trackMouseEvent = new()
            {
                cbSize = (uint)sizeof(TRACKMOUSEEVENT),
                dwFlags = TRACKMOUSEEVENT_FLAGS.TME_HOVER,
                hwndTrack = (HWND)_adornerWindow.Handle,
                dwHoverTime = 100
            };

            PInvoke.TrackMouseEvent(ref _trackMouseEvent);
        }
    }

    private void UnHookMouseEvent() => _trackingMouseEvent = false;

    private void OnDragDrop(DragEventArgs e)
    {
        _validDragArgs = null;

        Behavior? behavior = GetAppropriateBehavior(_hitTestedGlyph);
        if (behavior is null)
        {
            return;
        }

        behavior.OnDragDrop(_hitTestedGlyph, e);
    }

    private void PropagatePaint(PaintEventArgs pe)
    {
        for (int i = 0; i < Adorners.Count; i++)
        {
            if (!Adorners[i].Enabled)
            {
                continue;
            }

            for (int j = Adorners[i].Glyphs.Count - 1; j >= 0; j--)
            {
                Adorners[i].Glyphs[j].Paint(pe);
            }
        }
    }

    private void TestHook_GetRecentSnapLines(ref Message m)
    {
        string snapLineInfo = string.Empty;
        if (_testHook_RecentSnapLines is not null)
        {
            snapLineInfo = string.Join(Environment.NewLine, _testHook_RecentSnapLines) + Environment.NewLine;
        }

        TestHook_SetText(ref m, snapLineInfo);
    }

    private static void TestHook_SetText(ref Message m, string text)
    {
        if (m.LParamInternal == 0)
        {
            m.ResultInternal = (LRESULT)((text.Length + 1) * sizeof(char));
            return;
        }

        if ((int)m.WParamInternal < text.Length + 1)
        {
            m.ResultInternal = (LRESULT)(-1);
            return;
        }

        // Copy the name into the given IntPtr
        char[] nullChar = [(char)0];
        byte[] nullBytes;
        byte[] bytes;

        bytes = Encoding.Unicode.GetBytes(text);
        nullBytes = Encoding.Unicode.GetBytes(nullChar);

        Marshal.Copy(bytes, 0, m.LParamInternal, bytes.Length);
        Marshal.Copy(nullBytes, 0, m.LParamInternal + (nint)bytes.Length, nullBytes.Length);
        m.ResultInternal = (LRESULT)((bytes.Length + nullBytes.Length) / sizeof(char));
    }

    private void TestHook_GetAllSnapLines(ref Message m)
    {
        IDesignerHost? host = _serviceProvider.GetService<IDesignerHost>();
        if (host is null)
        {
            return;
        }

        StringBuilder snapLineInfo = new();
        foreach (Component comp in host.Container.Components)
        {
            if (comp is not Control)
            {
                continue;
            }

            if (host.GetDesigner(comp) is ControlDesigner designer)
            {
                foreach (SnapLine line in designer.SnapLinesInternal)
                {
                    snapLineInfo.Append($"{line}\tAssociated Control = {designer.Control.Name}:::");
                }
            }
        }

        TestHook_SetText(ref m, snapLineInfo.ToString());
    }

    private void OnDragOver(DragEventArgs e)
    {
        // cache off our validDragArgs so we can re-fabricate enter/leave drag events
        _validDragArgs = e;
        Behavior? behavior = GetAppropriateBehavior(_hitTestedGlyph);

        if (behavior is null)
        {
            e.Effect = DragDropEffects.None;
            return;
        }

        if (_hitTestedGlyph is null ||
           (_hitTestedGlyph is not null && !_dragEnterReplies.Contains(_hitTestedGlyph)))
        {
            behavior.OnDragOver(_hitTestedGlyph, e);
        }
        else
        {
            e.Effect = DragDropEffects.None;
        }
    }

    private void OnGiveFeedback(GiveFeedbackEventArgs e)
        => GetAppropriateBehavior(_hitTestedGlyph)?.OnGiveFeedback(_hitTestedGlyph, e);

    private void OnQueryContinueDrag(QueryContinueDragEventArgs e)
        => GetAppropriateBehavior(_hitTestedGlyph)?.OnQueryContinueDrag(_hitTestedGlyph, e);

    private void OnUserPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
    {
        SyncSelection();
        DesignerUtils.SyncBrushes();
    }
}
